1. Field of the Invention
The present invention relates to the field of magnetic recording, particularly to testers for magnetic read-write heads and computer hard disks.
2. Description of Prior Art
Prior to assembling computer disk drives, their main components, i.e., magnetic read-write heads and magnetic disks, are usually checked on magnetic head and disk testers. Such testers normally have a positioning mechanism required for accurately positioning a read-write gap of a magnetic read-write head above a specified track of a disk.
One known magnetic head and disk tester, is disclosed in U.S. patent application Ser. No. 5,254,946, granted 1993 Oct. 19 to by Guzik. A positioning device of this tester includes a base plate which slidingly supports a moveable housing which can slide along the base plate in one direction: the base rotate supports a rotatable platform. The rotatable platform rigidly and releasably supports a mechanical arm which extends radially inwardly towards the center of rotation of the rotatable platform and supports a head holder with a read-write head on its free end in such a position that the read-write gap of the head coincides with the position of the center of rotation of the rotary platform.
Positioning of the head to a position required for testing is performed by controlling displacements of the moveable housing (for shifting the head from track to track) and rotations of the rotatable platform. Also controlled are the mechanical arm and the head holder with the head supported by the rotatable platform (for setting a skew angle specified for the particular track).
However, the radial arm and head holder have fixed positions with respect to the rotatable platform. Therefore, an essential disadvantage of this design is that an access is available only to the upper side of the mechanical arm and, therefore, the head to be tested can be connected and disconnected to and from the mechanical arm only from above. This means that only one head which is positioned on the upper side of the mechanical arm can be tested one at a time. As a result, a head replacement operation must be performed very frequently. Moreover, the test head can interact only with one side of the disk. If the test object is a disk, the disk has to be turned over to test its bottom surface.
Furthermore, since the heads are replaced in a position close to their working position over the disk, there is a risk of damaging delicate and expensive parts of the tester.